-LRB- CNN -RRB- -- Manny Pacquiao is threatening Floyd Mayweather Jr. with legal action following a row over drugs testing which leaves their proposed super-bout next year in doubt .

Pacquiao is refusing to agree to a demand by the Mayweather camp to undergo Olympic style blood-screening in the run up to the fight , which is penciled in for the MGM Grand in Las Vegas on March 13 .

Boxing commentators had suggested that the war of words was a pre-fight tactic by the Mayweather camp and his promoter , Golden Boy Promotions , to unsettle the Filipino , who has hit back with an angry statement on his personal Web site .

`` Enough is enough . These people , Mayweather Sr , Jr , and Golden Boy Promotions , think it is a joke and a right to accuse someone wrongly of using steroids or other performance-enhancing drugs , '' it read .

`` I have tried to just brush it off as a mere pre-fight ploy but I think they have gone overboard ''

Pacquiao , who became a five-weight world champion by beating Puerto Rican Miguel Cotto in November , claimed he would now be calling in the lawyers .

`` I have instructed my promoter , Bob Arum , head of Top Rank Inc , to help me out in the filing of the case as soon as possible because I have had people coming over to me now asking if I really take performance-enhancing drugs and I have cheated my way into becoming the number one boxer in the world .

`` I maintain and assure everyone that I have not used any form or kind of steroids and that my way to the top is a result of hard work , hard work , hard work and a lot of blood spilled from my past battles in the ring , not outside of it .

`` I have no idea what steroids look like and my fear in God has kept me safe and victorious through all these years . ''

The row started earlier this week when Mayweather 's promoters Golden Boy Promotions went public with their demands for blood-testing , as mandated by the United States Anti-Doping Agency -LRB- USADA -RRB- and making it a condition before the super-fight went ahead .

But Pacquiao 's trainer Freddie Roach said this was not necessary under the rules governing fights in Nevada and was mind games by the Mayweather camp .

`` We have passed every test ever given to us . We go by the commission rules , since when does the fighter make up the rules ? , '' he said .

Mayweather himself has largely kept his counsel but told the Golden Boy Promotions Web site that he hoped his possible opponent would change his mind .

`` I understand Pacquiao not liking having his blood taken , because frankly I do n't know anyone who really does , '' Mayweather said .

`` I hope this is either some miscommunication or that Manny will change his mind and step up and allow these tests , which were good enough for all these other great athletes , to be performed by USADA . ''

But Pacquiao in his message posted on Christmas Day showed little sign of extending the festive spirit to the unbeaten Mayweather .

`` To Floyd , despite all these accusations , may your Christmas be merry and I will see you in court , soon , '' he added .

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Manny Pacquiao threatens Floyd Mayweather and his camp with legal action over a drug-testing row

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Pacquiao is angered by demands that he submit to blood-testing in the build-up to a proposed bout

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He claims to have instructed his promoter Bob Arum to file a law suit as soon as possible

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A welterweight match between Pacquiao and Mayweather is slated for Las Vegas on March 13 next year